(1) Field of the Invention
The present invention relates to a velocity measuring device and more particularly to a device for measuring the tangential turbulent velocity structure just above the surface of a vehicle moving in a conductive fluid medium.
(2) Description of the Prior Art
It is well known that the turbulent flow region around a body moving through a fluid exhibits a three dimensional velocity structure. Several techniques for measuring this velocity structure are currently available. These techniques generally include intrusive devices, e.g., hot wire anemometers, Pitot tubes, AC and DC electric and magnetic sensors, and propellers. The fluid velocity structure can also be measured in three dimensions for scale model structures with a Laser Doppler Velocimeter (LDV). However, the LDV is generally used externally to measure fluid velocity in a laboratory water tunnel or the like. It is not practical, however, to use a LDV on a full size, seagoing vessel as the LDV would have to be mounted outboard of, and close to, the hull of the vessel. What is required is a device which overcomes the inherent difficulties associated with earlier fluid velocity measurement techniques and which also allows measurement of the tangential velocity components of a full size vessel under real at-sea operating conditions.